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| Titel |
Substorm behavior of the auroral electrojet indices |
| VerfasserIn |
J. W. Gjerloev, R. A. Hoffman, M. M. Friel, L. A. Frank, J. B. Sigwarth |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 22, no. 6 ; Nr. 22, no. 6 (2004-06-14), S.2135-2149 |
| Datensatznummer |
250014906
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| Publikation (Nr.) |
 copernicus.org/angeo-22-2135-2004.pdf |
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| Zusammenfassung |
| The behavior of the auroral electrojet indices AU and AL
during classical substorms is investigated by the use of global auroral
images. A superposition of the 12 AE stations onto global auroral images and
identification of the AL and AU contributing stations enable an
understanding of the temporal as well as spatial behavior of the indices
with respect to the substorm coordinate system and timeframe. Based on this
simple technique it was found that at substorm onset the AL contributing
station makes a characteristic jump from a location near the dawn terminator
to the onset region, typically bypassing one or more AE stations. During the
expansion phase this station typically lies at the poleward edge of the
surge region. This is the location of the intense substorm current wedge
electrojet in the semiempirical self-consistent substorm model of the
three-dimensional current system by Gjerloev and Hoffman (2002). This current wedge is fed
primarily pre-midnight by an imbalance of the Region 0 and Region 1
field-aligned currents, not from the dawnside westward electrojet. Then
during the early recovery phase the AL contributing station jumps back to
the dawn sector. The defining AU station does not show any similar
systematic behavior. We also find that the dawn side westward electrojet
seems to be unaffected by the introduction of the substorm current wedge.
According to our model, much of this current is closed to the magnetosphere
as it approaches midnight from dawn. Based on the characteristics of the AL
station jumps, the behavior of the dawn-side electrojet, and the
understanding of the three-dimensional substorm current system from our
model, we provide additional experimental evidence for, and an understanding
of, the concept of the two component westward electrojet, as suggested by
Kamide and Kokubun (1996). |
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